Jatropha curcas attracts attention as biological resources for production of biodiesel fuel because it is able to produce a non-edible Jatropha oil. Further, Jatropha is known as a plant that can be cultivated even at locations unsuited for growth of other crops in terms of water and inorganic nutrients, and is believed to be very beneficial for effective utilization of semi-arid regions and for greening. On the other hand, although Jatropha plants grow in barrens, production efficiency of oils by natural cultivating is not high because fruition of the plants is once a year and the size of the fruit is significantly smaller than that of palm. For this reason, development of highly productive Jatropha is demanded.
As one measure for improving the production efficiency of a Jatropha oil, a method of transforming Jatropha so that acetyl CoA carboxylase (ACCase) can be overexpressed for increasing the oil content of the seed is known, for example, as proposed in PTL 1.
On the other hand, from the view point of enhancement of growth of Jatropha itself, it is also conceivable to impart environmental stress resistance that ensures high viability even in an environment of water shortage or the like.
As an environmental stress resistant gene recombinant plant, the one wherein the stress responsive signaling intensity and mechanism are modified so as to be adaptive or responsive to environmental stresses such as dry stress, a method for improvement to achieve overproduction of a protein molecule involved in resistance (a protein responding to environmental stresses) and the like are conceivable.
For example, NPL 1 reports, regarding a mechanism of controlling dry stress resistance in Arabidopsis thaliana, that a NF-YA5 transcription factor is ABA-dependent and is strongly induced by dry stress, and that transformed Arabidopsis thaliana overexpressing NF-YA5 is superior to wild-type Arabidopsis thaliana in resistance to dry stress.
Here, abscisic acid (ABA) is a plant hormone that is involved in seed dormancy, opening/closing of stoma and osmotic stress resistance, and ABA is known to be deeply involved in expression of a group of stress responsive genes.
As a method of preparing environmental stress resistant Arabidopsis thaliana, PTL 2 proposes a method of utilizing an activating function of a group of genes under the control of a transcription factor that activates transcription by binding with a cis element existing upstream the gene encoding a stress responsive protein expressed due to an environmental stress (a stress responsive transcription factor). Concretely, a SRK2C gene is disclosed as a novel gene encoding a signaling factor that induces expression of DREB/CBF which is a stress responsive transcription factor, and also it is disclosed that Arabidopsis thaliana transformed to overexpress the SRK2C gene shows dominantly high survival rate in comparison with a control even after stopping of water supply.
Further, NPL 2 reports that a corn NF-YB factor was identified, and a corn transformed by using this showed higher productivity under the condition of water shortage in comparison with the wild type.
Also, NPL 3 reports about Arabidopsis thaliana that nutrient growth and seed yield significantly decrease in an individual wherein the gene encoding phosphopantetheine adenylyltransferase (PPAT) is broken (a ppat-1 mutant) (FIG. 2), while on the contrary, in an individual overexpressing PPAT (an OE strain), the effect of enhancing salts resistance and osmotic resistance (test using mannitol) is obtained in comparison with the wild type, and growth is promoted in comparison with the wild type (see FIGS. 3 and 4).
The PPAT used herein, which is also abbreviated as AtCoaD, is an enzyme involved in biosynthesis of coenzyme A. Coenzyme A is biosynthesized from pantothenic acid as shown in FIG. 1, and PPAT catalyzes an exchange reaction between 4′-phosphopantetheine and dephospho coenzyme A. Coenzyme A consists of pantothenic acid, adenosine diphosphate and 2-thioxy ethaneamine, and is represented by the chemical formula C21H36P3N7O16S. This participates in a variety of metabolic reactions by binding of an acyl group of various compounds to its terminal thiol group by a thioester bond. Representatively, it is a coenzyme that is involved in the TCA cycle functioning commonly in prokaryotic and eukaryotic cells.